Deep fat frying is a common method of cooking food which is frequently used in fast food restaurants serving potatoes and other food items, such as chicken, fish, onion rings, and the like, which are usually covered with breading or batter. During the deep fat frying operation, these foods tend to shed particles in the form of pieces of the food items, starch granules from potatoes, flakes of breading or batter, etc. These particles continue to cook and will eventually carbonize or char if they stay in the cooking oil, and have a deleterious effect on subsequent food cooking. In particular, the overheated organic materials accelerate breakdown of the cooking oil, causing hydrolysis, oxidation, and polymerization thereof. Visible signs of breakdown soon appear in the form of smoking, uneven or almost no browning of the food, and in the final stages, foaming of the cooking oil itself. Filtering these particles from the cooking oil on a regular basis avoids or delays the difficulties, and extends the life of the cooking oil. Filtering of the cooking oil also extends the life and increases the efficiency of the fryer inasmuch as carbonized food particles assist development of polymers of the fats which coat the heating elements of the fryer, decreasing its efficiency. Finally, foods fried in clean cooking oil are of higher quality, and this is of utmost importance to the operator of a deep fat frying cooker.
It is well-known that regular filtering of the cooking oil to remove particulate contaminants therefrom will extend the life of the cooking oil, contribute to the efficient operation of the fryer, and improve the quality of the food products cooked therein. Several different types of apparatus exist in the prior art for accomplishing filtration of cooking oil, and the prior art devices encompass a broad range from a simple strainer through which the cooking oil is poured to an apparatus including a tank into which the cooking oil may be drained, filter papers and supporting assemblies, and motor driven pumps for moving the cooking oil from the fryer into the tank and for drawing the fat through the filter paper and returning it to the fryer. However, none of the known apparatus fully satisfy the needs of commercial establishments utilizing deep fat fryers and desiring to filter the cooking oil used therein.
It should be noted that in order to maximize the benefits of filtering cooking oil, it is often necessary to filter the cooking oil several times a day. The cooking oil must be in liquid form and is, therefore, generally hot during filtering and it is important that the filter apparatus minimize the possibility of the user being burned by the hot cooking oil or by parts of the filter apparatus which are made hot through contact with the cooking oil. The filter apparatus must be easy to use, and in particular, it must be easy to install and replace the filter element, even if it should become clogged in the midst of filtering a batch of hot cooking oil. It must also be easy to clean the filter apparatus. And, of course, the filter must operate in an efficient and dependable manner to quickly and effectively filter the cooking oil.